SUBJECTS AND METHODS: The direct and telemetered lead impedances were measured at the time of the initial implantation. One-hundred and five patients (mean age: 62.5±13.5 years, 47 males, 47 atrial leads and 105 ventricular leads) who were without lead failure for more than 4 years since the initial implantation were included in the study. Afterwards, the telemetered lead impedance was examined at 2-month and at 12-month after implantation and then annually for 4 years in all the patients at a pacemaker clinic.

RESULTS: At the initial implantation, the direct lead impedance and the telemetered lead impedance were 470.2±12.2omega and 540.9±11.6omega, respectively, in the atrial leads (r=0.72, p<0.01) and 623.7±14.6omega and 717.1±17.3omega, respectively, in the ventricular leads (r=0.82, p<0.01). In the atrial leads, the mean telemetered lead impedance rose to 583.0±14.0omega (p<0.01 vs baseline) at 2 months and it stabilized thereafter (p=NS). In contrast, the mean lead impedance was decreased to 653.6±15.6omega (p<0.01 vs baseline) at the 2-month follow-up, and then it stabilized in the ventricular leads (p=NS).

CONCLUSION: There was a good correlation between the direct and telemetered lead impedance, and there was a different tendency for the change of lead impedance during the lead maturation between the atrial and ventricular leads. The telemetered lead impedance was substantially stable since the 2 months after the implantation.